The present invention generally relates to a lens array for reading information employed in a copying machine, a facsimile machine, a printer or the like and also to a manufacturing method thereof.
Conventionally, as a lens array for reading information, there have been generally employed a lens array which is made by arranging a number of gradient index lenses (manufactured by Nippon Itagarasu Kabushiki Kaisha under the trademark SELFOC lens array, hereinafter referred to as the first prior art), or a lens array which is made by arranging a number of combinations of an upper pillar lens and a lower pillar lens as disclosed in Japanese Patent Laid-Open Publications No. 53-122426, No. 55-83071, and so on (hereinafter referred to as the second prior art).
However, the first prior art has problems such as a complicated manufacturing method and high cost.
On the other hand, in the second prior art, the pillar lens b is generally formed by pressing a transparent plastic material a as shown in FIG. 9 of Publication No. 55-83071. In this case, accuracy of a curvature of the lens and mass production are not ensured. Moreover, since it is difficult to press glass to form the pillar lens, light transmission is worse.